/*
 * contrib/intarray/_intbig_gist.c
 */
#include "postgres.h"

#include "access/gist.h"
#include "access/stratnum.h"

#include "_int.h"

#define GETENTRY(vec,pos) ((GISTTYPE *) DatumGetPointer((vec)->vector[(pos)].key))
/*
** _intbig methods
*/
PG_FUNCTION_INFO_V1(g_intbig_consistent);
PG_FUNCTION_INFO_V1(g_intbig_compress);
PG_FUNCTION_INFO_V1(g_intbig_decompress);
PG_FUNCTION_INFO_V1(g_intbig_penalty);
PG_FUNCTION_INFO_V1(g_intbig_picksplit);
PG_FUNCTION_INFO_V1(g_intbig_union);
PG_FUNCTION_INFO_V1(g_intbig_same);

/* Number of one-bits in an unsigned byte */
static const uint8 number_of_ones[256] = {
    0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4,
    1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
    1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
    2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
    1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
    2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
    2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
    3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
    1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
    2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
    2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
    3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
    2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
    3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
    3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
    4, 5, 5, 6, 5, 6, 6, 7, 5, 6, 6, 7, 6, 7, 7, 8
};

PG_FUNCTION_INFO_V1(_intbig_in);
PG_FUNCTION_INFO_V1(_intbig_out);

Datum
_intbig_in(PG_FUNCTION_ARGS)
{
    ereport(ERROR,
            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
             errmsg("_intbig_in() not implemented")));
    PG_RETURN_DATUM(0);
}

Datum
_intbig_out(PG_FUNCTION_ARGS)
{
    ereport(ERROR,
            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
             errmsg("_intbig_out() not implemented")));
    PG_RETURN_DATUM(0);
}


/*********************************************************************
** intbig functions
*********************************************************************/
static bool
_intbig_overlap(GISTTYPE *a, ArrayType *b)
{
    int            num = ARRNELEMS(b);
    int32       *ptr = ARRPTR(b);

    CHECKARRVALID(b);

    while (num--)
    {
        if (GETBIT(GETSIGN(a), HASHVAL(*ptr)))
            return true;
        ptr++;
    }

    return false;
}

static bool
_intbig_contains(GISTTYPE *a, ArrayType *b)
{
    int            num = ARRNELEMS(b);
    int32       *ptr = ARRPTR(b);

    CHECKARRVALID(b);

    while (num--)
    {
        if (!GETBIT(GETSIGN(a), HASHVAL(*ptr)))
            return false;
        ptr++;
    }

    return true;
}

Datum
g_intbig_same(PG_FUNCTION_ARGS)
{
    GISTTYPE   *a = (GISTTYPE *) PG_GETARG_POINTER(0);
    GISTTYPE   *b = (GISTTYPE *) PG_GETARG_POINTER(1);
    bool       *result = (bool *) PG_GETARG_POINTER(2);

    if (ISALLTRUE(a) && ISALLTRUE(b))
        *result = true;
    else if (ISALLTRUE(a))
        *result = false;
    else if (ISALLTRUE(b))
        *result = false;
    else
    {
        int32        i;
        BITVECP        sa = GETSIGN(a),
                    sb = GETSIGN(b);

        *result = true;
        LOOPBYTE
        {
            if (sa[i] != sb[i])
            {
                *result = false;
                break;
            }
        }
    }
    PG_RETURN_POINTER(result);
}

Datum
g_intbig_compress(PG_FUNCTION_ARGS)
{
    GISTENTRY  *entry = (GISTENTRY *) PG_GETARG_POINTER(0);

    if (entry->leafkey)
    {
        GISTENTRY  *retval;
        ArrayType  *in = DatumGetArrayTypeP(entry->key);
        int32       *ptr;
        int            num;
        GISTTYPE   *res = (GISTTYPE *) palloc0(CALCGTSIZE(0));

        CHECKARRVALID(in);
        if (ARRISEMPTY(in))
        {
            ptr = NULL;
            num = 0;
        }
        else
        {
            ptr = ARRPTR(in);
            num = ARRNELEMS(in);
        }
        SET_VARSIZE(res, CALCGTSIZE(0));

        while (num--)
        {
            HASH(GETSIGN(res), *ptr);
            ptr++;
        }

        retval = (GISTENTRY *) palloc(sizeof(GISTENTRY));
        gistentryinit(*retval, PointerGetDatum(res),
                      entry->rel, entry->page,
                      entry->offset, FALSE);

        if (in != DatumGetArrayTypeP(entry->key))
            pfree(in);

        PG_RETURN_POINTER(retval);
    }
    else if (!ISALLTRUE(DatumGetPointer(entry->key)))
    {
        GISTENTRY  *retval;
        int            i;
        BITVECP        sign = GETSIGN(DatumGetPointer(entry->key));
        GISTTYPE   *res;

        LOOPBYTE
        {
            if ((sign[i] & 0xff) != 0xff)
                PG_RETURN_POINTER(entry);
        }

        res = (GISTTYPE *) palloc(CALCGTSIZE(ALLISTRUE));
        SET_VARSIZE(res, CALCGTSIZE(ALLISTRUE));
        res->flag = ALLISTRUE;

        retval = (GISTENTRY *) palloc(sizeof(GISTENTRY));
        gistentryinit(*retval, PointerGetDatum(res),
                      entry->rel, entry->page,
                      entry->offset, FALSE);

        PG_RETURN_POINTER(retval);
    }

    PG_RETURN_POINTER(entry);
}


static int32
sizebitvec(BITVECP sign)
{
    int32        size = 0,
                i;

    LOOPBYTE
        size += number_of_ones[(unsigned char) sign[i]];
    return size;
}

static int
hemdistsign(BITVECP a, BITVECP b)
{
    int            i,
                diff,
                dist = 0;

    LOOPBYTE
    {
        diff = (unsigned char) (a[i] ^ b[i]);
        dist += number_of_ones[diff];
    }
    return dist;
}

static int
hemdist(GISTTYPE *a, GISTTYPE *b)
{
    if (ISALLTRUE(a))
    {
        if (ISALLTRUE(b))
            return 0;
        else
            return SIGLENBIT - sizebitvec(GETSIGN(b));
    }
    else if (ISALLTRUE(b))
        return SIGLENBIT - sizebitvec(GETSIGN(a));

    return hemdistsign(GETSIGN(a), GETSIGN(b));
}

Datum
g_intbig_decompress(PG_FUNCTION_ARGS)
{
    PG_RETURN_DATUM(PG_GETARG_DATUM(0));
}

static int32
unionkey(BITVECP sbase, GISTTYPE *add)
{
    int32        i;
    BITVECP        sadd = GETSIGN(add);

    if (ISALLTRUE(add))
        return 1;
    LOOPBYTE
        sbase[i] |= sadd[i];
    return 0;
}

Datum
g_intbig_union(PG_FUNCTION_ARGS)
{
    GistEntryVector *entryvec = (GistEntryVector *) PG_GETARG_POINTER(0);
    int           *size = (int *) PG_GETARG_POINTER(1);
    BITVEC        base;
    int32        i,
                len;
    int32        flag = 0;
    GISTTYPE   *result;

    MemSet((void *) base, 0, sizeof(BITVEC));
    for (i = 0; i < entryvec->n; i++)
    {
        if (unionkey(base, GETENTRY(entryvec, i)))
        {
            flag = ALLISTRUE;
            break;
        }
    }

    len = CALCGTSIZE(flag);
    result = (GISTTYPE *) palloc(len);
    SET_VARSIZE(result, len);
    result->flag = flag;
    if (!ISALLTRUE(result))
        memcpy((void *) GETSIGN(result), (void *) base, sizeof(BITVEC));
    *size = len;

    PG_RETURN_POINTER(result);
}

Datum
g_intbig_penalty(PG_FUNCTION_ARGS)
{
    GISTENTRY  *origentry = (GISTENTRY *) PG_GETARG_POINTER(0); /* always ISSIGNKEY */
    GISTENTRY  *newentry = (GISTENTRY *) PG_GETARG_POINTER(1);
    float       *penalty = (float *) PG_GETARG_POINTER(2);
    GISTTYPE   *origval = (GISTTYPE *) DatumGetPointer(origentry->key);
    GISTTYPE   *newval = (GISTTYPE *) DatumGetPointer(newentry->key);

    *penalty = hemdist(origval, newval);
    PG_RETURN_POINTER(penalty);
}


typedef struct
{
    OffsetNumber pos;
    int32        cost;
} SPLITCOST;

static int
comparecost(const void *a, const void *b)
{
    return ((const SPLITCOST *) a)->cost - ((const SPLITCOST *) b)->cost;
}


Datum
g_intbig_picksplit(PG_FUNCTION_ARGS)
{
    GistEntryVector *entryvec = (GistEntryVector *) PG_GETARG_POINTER(0);
    GIST_SPLITVEC *v = (GIST_SPLITVEC *) PG_GETARG_POINTER(1);
    OffsetNumber k,
                j;
    GISTTYPE   *datum_l,
               *datum_r;
    BITVECP        union_l,
                union_r;
    int32        size_alpha,
                size_beta;
    int32        size_waste,
                waste = -1;
    int32        nbytes;
    OffsetNumber seed_1 = 0,
                seed_2 = 0;
    OffsetNumber *left,
               *right;
    OffsetNumber maxoff;
    BITVECP        ptr;
    int            i;
    SPLITCOST  *costvector;
    GISTTYPE   *_k,
               *_j;

    maxoff = entryvec->n - 2;
    nbytes = (maxoff + 2) * sizeof(OffsetNumber);
    v->spl_left = (OffsetNumber *) palloc(nbytes);
    v->spl_right = (OffsetNumber *) palloc(nbytes);

    for (k = FirstOffsetNumber; k < maxoff; k = OffsetNumberNext(k))
    {
        _k = GETENTRY(entryvec, k);
        for (j = OffsetNumberNext(k); j <= maxoff; j = OffsetNumberNext(j))
        {
            size_waste = hemdist(_k, GETENTRY(entryvec, j));
            if (size_waste > waste)
            {
                waste = size_waste;
                seed_1 = k;
                seed_2 = j;
            }
        }
    }

    left = v->spl_left;
    v->spl_nleft = 0;
    right = v->spl_right;
    v->spl_nright = 0;

    if (seed_1 == 0 || seed_2 == 0)
    {
        seed_1 = 1;
        seed_2 = 2;
    }

    /* form initial .. */
    if (ISALLTRUE(GETENTRY(entryvec, seed_1)))
    {
        datum_l = (GISTTYPE *) palloc(GTHDRSIZE);
        SET_VARSIZE(datum_l, GTHDRSIZE);
        datum_l->flag = ALLISTRUE;
    }
    else
    {
        datum_l = (GISTTYPE *) palloc(GTHDRSIZE + SIGLEN);
        SET_VARSIZE(datum_l, GTHDRSIZE + SIGLEN);
        datum_l->flag = 0;
        memcpy((void *) GETSIGN(datum_l), (void *) GETSIGN(GETENTRY(entryvec, seed_1)), sizeof(BITVEC));
    }
    if (ISALLTRUE(GETENTRY(entryvec, seed_2)))
    {
        datum_r = (GISTTYPE *) palloc(GTHDRSIZE);
        SET_VARSIZE(datum_r, GTHDRSIZE);
        datum_r->flag = ALLISTRUE;
    }
    else
    {
        datum_r = (GISTTYPE *) palloc(GTHDRSIZE + SIGLEN);
        SET_VARSIZE(datum_r, GTHDRSIZE + SIGLEN);
        datum_r->flag = 0;
        memcpy((void *) GETSIGN(datum_r), (void *) GETSIGN(GETENTRY(entryvec, seed_2)), sizeof(BITVEC));
    }

    maxoff = OffsetNumberNext(maxoff);
    /* sort before ... */
    costvector = (SPLITCOST *) palloc(sizeof(SPLITCOST) * maxoff);
    for (j = FirstOffsetNumber; j <= maxoff; j = OffsetNumberNext(j))
    {
        costvector[j - 1].pos = j;
        _j = GETENTRY(entryvec, j);
        size_alpha = hemdist(datum_l, _j);
        size_beta = hemdist(datum_r, _j);
        costvector[j - 1].cost = Abs(size_alpha - size_beta);
    }
    qsort((void *) costvector, maxoff, sizeof(SPLITCOST), comparecost);

    union_l = GETSIGN(datum_l);
    union_r = GETSIGN(datum_r);

    for (k = 0; k < maxoff; k++)
    {
        j = costvector[k].pos;
        if (j == seed_1)
        {
            *left++ = j;
            v->spl_nleft++;
            continue;
        }
        else if (j == seed_2)
        {
            *right++ = j;
            v->spl_nright++;
            continue;
        }
        _j = GETENTRY(entryvec, j);
        size_alpha = hemdist(datum_l, _j);
        size_beta = hemdist(datum_r, _j);

        if (size_alpha < size_beta + WISH_F(v->spl_nleft, v->spl_nright, 0.00001))
        {
            if (ISALLTRUE(datum_l) || ISALLTRUE(_j))
            {
                if (!ISALLTRUE(datum_l))
                    MemSet((void *) union_l, 0xff, sizeof(BITVEC));
            }
            else
            {
                ptr = GETSIGN(_j);
                LOOPBYTE
                    union_l[i] |= ptr[i];
            }
            *left++ = j;
            v->spl_nleft++;
        }
        else
        {
            if (ISALLTRUE(datum_r) || ISALLTRUE(_j))
            {
                if (!ISALLTRUE(datum_r))
                    MemSet((void *) union_r, 0xff, sizeof(BITVEC));
            }
            else
            {
                ptr = GETSIGN(_j);
                LOOPBYTE
                    union_r[i] |= ptr[i];
            }
            *right++ = j;
            v->spl_nright++;
        }
    }

    *right = *left = FirstOffsetNumber;
    pfree(costvector);

    v->spl_ldatum = PointerGetDatum(datum_l);
    v->spl_rdatum = PointerGetDatum(datum_r);

    PG_RETURN_POINTER(v);
}

Datum
g_intbig_consistent(PG_FUNCTION_ARGS)
{
    GISTENTRY  *entry = (GISTENTRY *) PG_GETARG_POINTER(0);
    ArrayType  *query = PG_GETARG_ARRAYTYPE_P(1);
    StrategyNumber strategy = (StrategyNumber) PG_GETARG_UINT16(2);

    /* Oid        subtype = PG_GETARG_OID(3); */
    bool       *recheck = (bool *) PG_GETARG_POINTER(4);
    bool        retval;

    /* All cases served by this function are inexact */
    *recheck = true;

    if (ISALLTRUE(DatumGetPointer(entry->key)))
        PG_RETURN_BOOL(true);

    if (strategy == BooleanSearchStrategy)
    {
        retval = signconsistent((QUERYTYPE *) query,
                                GETSIGN(DatumGetPointer(entry->key)),
                                false);
        PG_FREE_IF_COPY(query, 1);
        PG_RETURN_BOOL(retval);
    }

    CHECKARRVALID(query);

    switch (strategy)
    {
        case RTOverlapStrategyNumber:
            retval = _intbig_overlap((GISTTYPE *) DatumGetPointer(entry->key), query);
            break;
        case RTSameStrategyNumber:
            if (GIST_LEAF(entry))
            {
                int            i,
                            num = ARRNELEMS(query);
                int32       *ptr = ARRPTR(query);
                BITVEC        qp;
                BITVECP        dq,
                            de;

                memset(qp, 0, sizeof(BITVEC));

                while (num--)
                {
                    HASH(qp, *ptr);
                    ptr++;
                }

                de = GETSIGN((GISTTYPE *) DatumGetPointer(entry->key));
                dq = qp;
                retval = true;
                LOOPBYTE
                {
                    if (de[i] != dq[i])
                    {
                        retval = false;
                        break;
                    }
                }

            }
            else
                retval = _intbig_contains((GISTTYPE *) DatumGetPointer(entry->key), query);
            break;
        case RTContainsStrategyNumber:
        case RTOldContainsStrategyNumber:
            retval = _intbig_contains((GISTTYPE *) DatumGetPointer(entry->key), query);
            break;
        case RTContainedByStrategyNumber:
        case RTOldContainedByStrategyNumber:
            if (GIST_LEAF(entry))
            {
                int            i,
                            num = ARRNELEMS(query);
                int32       *ptr = ARRPTR(query);
                BITVEC        qp;
                BITVECP        dq,
                            de;

                memset(qp, 0, sizeof(BITVEC));

                while (num--)
                {
                    HASH(qp, *ptr);
                    ptr++;
                }

                de = GETSIGN((GISTTYPE *) DatumGetPointer(entry->key));
                dq = qp;
                retval = true;
                LOOPBYTE
                {
                    if (de[i] & ~dq[i])
                    {
                        retval = false;
                        break;
                    }
                }
            }
            else
                retval = _intbig_overlap((GISTTYPE *) DatumGetPointer(entry->key), query);
            break;
        default:
            retval = FALSE;
    }
    PG_FREE_IF_COPY(query, 1);
    PG_RETURN_BOOL(retval);
}
